Any ideas on how to lower my hydrocarbons at a idle? ZZ4. 219. 74219. air pump intact. Random tech Superram, Svo#24



Tia
Rich

 

Any fuel smells around the rear end of the car, or other gas leaks?


Other than that, buy a ZR-1 :jester

 

No smell of gas in the back end. I think I have a timming issue.

 

So, your car is running rich at idle. Start with all the things that would let extra fuel into the cylinders and unburned fuel out the tailpipe...

 

High HC is caused mostly by unburned gas. Check for any vacuum leaks and the other thing was the smell of gas but you don't have that. I couldn't read the test but if your CO is somewhat high the HC will be high at idle. A bottle of 100% rubbing alcohol will bring the CO down. Try these sites for some info.http://ca.autos.yahoo.com/010815/11/8ymx.html http://www.mr2.com/TEXT/SmogCheck.html:thumbs:
Good Luck

 

If you were stock, I'd say it didn't go closed loop or there was an open in your O2 circuit. If you have a scanner, post loop status & BLM #'s - you may need additional programming to take out fuel at idle or an adjustable regulator to lower pressure with those 24lb injectors.

 

Click on the picture for a better view.

 

:eek: 1700x2199 Pixels? I have a 19" monitor and it's way too big for that.It seems you have alot :eek: of unburned gas. High HC and low CO like yours would mean a lean condition.
I also found this statement:one cause of HC emissions at idle is weak or inadequate spark. High compression and a lean mixture will make it harder to get full ignition, as will fouled spark plugs. A long-duration or multiple-spark ignition system like those made by Crane or MSD will assure more complete combustion at low rpm and clean up some of those HC problems, in addition to giving you more power and cleaner spark plugs. Make sure you have fresh plugs in the engine for the test.

A more subtle factor that affects HC emissions is cam timing. Long duration cams with lots of overlap (where the intake and exhaust valves are open at the same time) increase HC because unburned fuel flows directly from the intake to the exhaust. This is great for top-end performance because it cools the exhaust valve and helps scavenge the cylinder of the waste gases from the previous power stroke. But it can kill you at the testing station.

Can you do anything about it? Yes. High-revving engines with heavy valve springs are notoriously hard on valve seats. The valves pound away at the seats and sink into the head. This tightens up the valve lash. Since many of these cams have long ramps at the ends of the valve events, this decreased clearance will actually increase the effective cam duration and consequently the overlap increases, too. In addition to increasing HC, this can also hurt low-end performance. Make sure your valves are adjusted correctly to prevent excessive overlap.
I don't know how much mods you have but I'd start checking these fist. And check out how strong the ignition is at idle. Throw some new plugs in before you take it back up.

 

My friend deals with this stuff all the time. If you like the way your car is running and don't want to go through a bunch of diagnostics and things mentioned in the previous post. You can increase your idle to about 1100 Rpm and that should get you through, then you can just reset it. The other possibility would be to advance your timing. Increasing the RPM should do it though :thumbs: .

 

I don't know about other states, but in Missouri you can't go over 850 rpms (idle) for emissions testing.


[Modified by STL94LT1, 1:53 AM 3/31/2003]

 

1100 is the limit here. I have decide to do the 870-165 swap and really dial the thing in.

 

:cheers: :confused:

 

Here is a simpler solution:

Dry gas (isopropyl alcohol) - Your gas level should be less than 1/4 full tank; put in about 10-15 bottles of dry gas. Also, the hotter you car runs, the lower you HC ppm will become, at the expense of your NoX count (but the tradeoff is not too significant, your allowed a significant amount of NoX ppm compared to HC ppm). Disable your primary fan and utilize your secondary fan which I believe turns on at around 235-240 degrees.

I used the above method with my 1989 camaro L98 and never exceeded 20 ppm (15 ppm was the lowest 1999) (limit 175ppm) with the NJ dyno testing. In fact, when that emmissions test was new, the system had the car retested because the HC count was too low. Without the dry gas and primary fan enabled, my car was in the range of 65-75 ppm.

As far as the alcohol affecting the seals, the fuel pump had over 150,000 miles before it was swapped for a Walbro and eventually sold in 2002 (had the car since 1994).

 

Soemthing that is often overlooked is that the fuel pressure regulator is set too high.

~ Purp :flag